/*
 * Copyright (C) 2008 ZXing authors
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.google.zxing.qrcode.camera;

import android.content.Context;
import android.graphics.ImageFormat;
import android.graphics.Point;
import android.graphics.Rect;
import android.hardware.Camera;
import android.os.Build;
import android.os.Handler;
import android.view.SurfaceHolder;

import java.io.IOException;

import org.apache.log4j.Level;
import org.apache.log4j.Logger;

/**
 * This object wraps the Camera service object and expects to be the only one talking to it. The implementation
 * encapsulates the steps needed to take preview-sized images, which are used for both preview and decoding.
 * 
 * @author dswitkin@google.com (Daniel Switkin)
 */
public final class CameraManager
{
    
    private static final Logger log = Logger.getLogger(CameraManager.class);
    
    static
    {
        log.setLevel(Level.OFF);
    }
    
    private static final int MIN_FRAME_WIDTH = 240;
    
    private static final int MIN_FRAME_HEIGHT = 240;
    
    private static final int MAX_FRAME_WIDTH = 480;
    
    private static final int MAX_FRAME_HEIGHT = 360;
    
    private static CameraManager cameraManager;
    
    static final int SDK_INT; // Later we can use Build.VERSION.SDK_INT
    static
    {
        int sdkInt;
        try
        {
            // sdkInt = Integer.parseInt(Build.VERSION.SDK);
            sdkInt = Build.VERSION.SDK_INT;
        }
        catch (NumberFormatException nfe)
        {
            // Just to be safe
            sdkInt = 10000;
        }
        SDK_INT = sdkInt;
    }
    
    // private final Context context;
    private final CameraConfigurationManager configManager;
    
    private Camera camera;
    
    private Rect framingRect;
    
    private Rect framingRectInPreview;
    
    private boolean initialized;
    
    private boolean previewing;
    
    private final boolean useOneShotPreviewCallback;
    
    /**
     * Preview frames are delivered here, which we pass on to the registered handler. Make sure to clear the handler so
     * it will only receive one message.
     */
    private final PreviewCallback previewCallback;
    
    /** Autofocus callbacks arrive here, and are dispatched to the Handler which requested them. */
    private final AutoFocusCallback autoFocusCallback;
    
    /**
     * Initializes this static object with the Context of the calling Activity.
     * 
     * @param context The Activity which wants to use the camera.
     */
    public static void init(Context context)
    {
        if (cameraManager == null)
        {
            cameraManager = new CameraManager(context);
        }
    }
    
    /**
     * Gets the CameraManager singleton instance.
     * 
     * @return A reference to the CameraManager singleton.
     */
    public static CameraManager get()
    {
        return cameraManager;
    }
    
    private CameraManager(Context context)
    {
        
        // this.context = context;
        this.configManager = new CameraConfigurationManager(context);
        
        // Camera.setOneShotPreviewCallback() has a race condition in Cupcake, so we use the older
        // Camera.setPreviewCallback() on 1.5 and earlier. For Donut and later, we need to use
        // the more efficient one shot callback, as the older one can swamp the system and cause it
        // to run out of memory. We can't use SDK_INT because it was introduced in the Donut SDK.
        // useOneShotPreviewCallback = Integer.parseInt(Build.VERSION.SDK) > Build.VERSION_CODES.CUPCAKE;
        // useOneShotPreviewCallback = Integer.parseInt(Build.VERSION.SDK) > 3; // 3 = Cupcake
        useOneShotPreviewCallback = Build.VERSION.SDK_INT > 3;
        
        previewCallback = new PreviewCallback(configManager, useOneShotPreviewCallback);
        autoFocusCallback = new AutoFocusCallback();
    }
    
    /**
     * Opens the camera driver and initializes the hardware parameters.
     * 
     * @param holder The surface object which the camera will draw preview frames into.
     * @throws IOException Indicates the camera driver failed to open.
     */
    public void openDriver(SurfaceHolder holder)
        throws IOException
    {
        if (camera == null)
        {
            camera = Camera.open();
            if (camera == null)
            {
                throw new IOException();
            }
            camera.setPreviewDisplay(holder);
            
            if (!initialized)
            {
                initialized = true;
                configManager.initFromCameraParameters(camera);
            }
            configManager.setDesiredCameraParameters(camera);
            
            // SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(context);
            // if (prefs.getBoolean(PreferencesActivity.KEY_FRONT_LIGHT, false)) {
            // FlashlightManager.enableFlashlight();
            // }
            FlashlightManager.enableFlashlight();
        }
    }
    
    /**
     * Closes the camera driver if still in use.
     */
    public void closeDriver()
    {
        if (camera != null)
        {
            FlashlightManager.disableFlashlight();
            camera.release();
            camera = null;
        }
    }
    
    /**
     * Asks the camera hardware to begin drawing preview frames to the screen.
     */
    public void startPreview()
    {
        if (camera != null && !previewing)
        {
            camera.startPreview();
            previewing = true;
        }
    }
    
    /**
     * Tells the camera to stop drawing preview frames.
     */
    public void stopPreview()
    {
        if (camera != null && previewing)
        {
            if (!useOneShotPreviewCallback)
            {
                camera.setPreviewCallback(null);
            }
            camera.stopPreview();
            previewCallback.setHandler(null, 0);
            autoFocusCallback.setHandler(null, 0);
            previewing = false;
        }
    }
    
    /**
     * A single preview frame will be returned to the handler supplied. The data will arrive as byte[] in the
     * message.obj field, with width and height encoded as message.arg1 and message.arg2, respectively.
     * 
     * @param handler The handler to send the message to.
     * @param message The what field of the message to be sent.
     */
    public void requestPreviewFrame(Handler handler, int message)
    {
        if (camera != null && previewing)
        {
            previewCallback.setHandler(handler, message);
            if (useOneShotPreviewCallback)
            {
                camera.setOneShotPreviewCallback(previewCallback);
            }
            else
            {
                camera.setPreviewCallback(previewCallback);
            }
        }
    }
    
    /**
     * Asks the camera hardware to perform an autofocus.
     * 
     * @param handler The Handler to notify when the autofocus completes.
     * @param message The message to deliver.
     */
    public void requestAutoFocus(Handler handler, int message)
    {
        if (camera != null && previewing)
        {
            autoFocusCallback.setHandler(handler, message);
            // Logger.d(TAG, "Requesting auto-focus callback");
            camera.autoFocus(autoFocusCallback);
        }
    }
    
    /**
     * Calculates the framing rect which the UI should draw to show the user where to place the barcode. This target
     * helps with alignment as well as forces the user to hold the device far enough away to ensure the image will be in
     * focus.
     * 
     * @return The rectangle to draw on screen in window coordinates.
     */
    public Rect getFramingRect()
    {
        Point screenResolution = configManager.getScreenResolution();
        if (framingRect == null)
        {
            if (camera == null)
            {
                return null;
            }
            int width = screenResolution.x * 3 / 4;
            if (width < MIN_FRAME_WIDTH)
            {
                width = MIN_FRAME_WIDTH;
            }
            else if (width > MAX_FRAME_WIDTH)
            {
                width = MAX_FRAME_WIDTH;
            }
            int height = screenResolution.y * 3 / 4;
            if (height < MIN_FRAME_HEIGHT)
            {
                height = MIN_FRAME_HEIGHT;
            }
            else if (height > MAX_FRAME_HEIGHT)
            {
                height = MAX_FRAME_HEIGHT;
            }
            int leftOffset = (screenResolution.x - width) / 2;
            int topOffset = (screenResolution.y - height) / 2;
            framingRect = new Rect(leftOffset, topOffset, leftOffset + width, topOffset + height);
            log.debug("Calculated framing rect: " + framingRect);
        }
        return framingRect;
    }
    
    /**
     * Like {@link #getFramingRect} but coordinates are in terms of the preview frame, not UI / screen.
     */
    public Rect getFramingRectInPreview()
    {
        if (framingRectInPreview == null)
        {
            Rect rect = new Rect(getFramingRect());
            Point cameraResolution = configManager.getCameraResolution();
            Point screenResolution = configManager.getScreenResolution();
            rect.left = rect.left * cameraResolution.x / screenResolution.x;
            rect.right = rect.right * cameraResolution.x / screenResolution.x;
            rect.top = rect.top * cameraResolution.y / screenResolution.y;
            rect.bottom = rect.bottom * cameraResolution.y / screenResolution.y;
            framingRectInPreview = rect;
        }
        return framingRectInPreview;
    }
    
    /**
     * Converts the result points from still resolution coordinates to screen coordinates.
     * 
     * @param points The points returned by the Reader subclass through Result.getResultPoints().
     * @return An array of Points scaled to the size of the framing rect and offset appropriately so they can be drawn
     *         in screen coordinates.
     */
    /*
     * public Point[] convertResultPoints(ResultPoint[] points) { Rect frame = getFramingRectInPreview(); int count =
     * points.length; Point[] output = new Point[count]; for (int x = 0; x < count; x++) { output[x] = new Point();
     * output[x].x = frame.left + (int) (points[x].getX() + 0.5f); output[x].y = frame.top + (int) (points[x].getY() +
     * 0.5f); } return output; }
     */
    
    /**
     * A factory method to build the appropriate LuminanceSource object based on the format of the preview buffers, as
     * described by Camera.Parameters.
     * 
     * @param data A preview frame.
     * @param width The width of the image.
     * @param height The height of the image.
     * @return A PlanarYUVLuminanceSource instance.
     */
    public PlanarYUVLuminanceSource buildLuminanceSource(byte[] data, int width, int height)
    {
        Rect rect = getFramingRectInPreview();
        int previewFormat = configManager.getPreviewFormat();
        String previewFormatString = configManager.getPreviewFormatString();
        switch (previewFormat)
        {
        // This is the standard Android format which all devices are REQUIRED to support.
        // In theory, it's the only one we should ever care about.
        // case PixelFormat.YCbCr_420_SP:
            case ImageFormat.NV21:
                // This format has never been seen in the wild, but is compatible as we only care
                // about the Y channel, so allow it.
                // case PixelFormat.YCbCr_422_SP:
            case ImageFormat.NV16:
                return new PlanarYUVLuminanceSource(data, width, height, rect.left, rect.top, rect.width(),
                    rect.height());
            default:
                // The Samsung Moment incorrectly uses this variant instead of the 'sp' version.
                // Fortunately, it too has all the Y data up front, so we can read it.
                if ("yuv420p".equals(previewFormatString))
                {
                    return new PlanarYUVLuminanceSource(data, width, height, rect.left, rect.top, rect.width(),
                        rect.height());
                }
        }
        throw new IllegalArgumentException("Unsupported picture format: " + previewFormat + '/' + previewFormatString);
    }
    
}
